/Engine/Plugins/Experimental/LandscapePatch/Source/LandscapePatch/Public/LandscapeTexturePatchPS.h
Flags that get packed into a bitfield because we're not allowed to use bool shader parameters:
enum EFlags { None = 0, RectangularFalloff = 1 << 0, ApplyPatchAlpha = 1 << 1, }